/**
 * struct TreeNode {
 *	int val;
 *	struct TreeNode *left;
 *	struct TreeNode *right;
 *	TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 * };
 */
class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param root TreeNode类 
     * @return int整型
     */
    int ret = -1010;
    int dfs(TreeNode* root)
    {
        if(root == nullptr)
        {
            return 0;
        }
        int l = max(0,dfs(root->left));
        int r = max(0,dfs(root->right));
        ret = max(ret,root->val + l + r);
        return root->val + max(l ,r);
    }
    int maxPathSum(TreeNode* root) {
        // write code here
        dfs(root);
        return ret;
    }
};